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Non Double-Layer Regime: a new laser driven ion acceleration mechanism toward TeV

Non Double-Layer Regime: a new laser driven ion acceleration mechanism toward TeV. outline. significance 、 implications 、 goals for high energetic ion beams one-stage acceleration ： target normal sheath acceleration (TNSA) 、 phase-stable acceleration or radiation pressure acceleration(RPA )

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Non Double-Layer Regime: a new laser driven ion acceleration mechanism toward TeV

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  1. Non Double-Layer Regime: a new laser driven ion acceleration mechanism toward TeV

  2. outline • significance、implications、goals for high energetic ion beams • one-stage acceleration：target normal sheath acceleration (TNSA)、phase-stable acceleration or radiation pressure acceleration(RPA) • multi-stage acceleration for TeV proton beam： non double layer regime • Tens TeV or even higher energetic heavy ion beam

  3. 1.Motivation and current situation of laser-plasma ion acceleration The produced high energetic ion by target normal sheath acceleration( TNSA）experimentally： • energy gain：67MeV for proton and 500MeV for Carbon ion. • acceleration field strength: 100 GV/m --10000 GV/m • energy spread: 20% • good repetitiveness applications：ion cancer therapy、fast ignition of thermonuclear fusion、high energy physics and astrophysics goals ：mono-energetic、collimated、higher energy、higher transfer efficiency

  4. TNSA 2.One stage acceleration Laser 2.1(a) TNSA Thick solid target Typical values:

  5. v Thin solid target 2.One stage acceleration 2.2 circularly polarized laser-thin target interaction for ion acceleration ------phase stable acceleration or radiation pressure acceleration From an immobile sheath to a moving sheath/double layer

  6. 2.One stage acceleration 2.2 circularly polarized laser-thin target interaction for ion acceleration ------phase stable acceleration or radiation pressure acceleration (a) The light pressure balances the electrostatic pressure to form double layer (electron and ion layer) structure, green：proton blue：electron matching condition:

  7. 2.One stage acceleration b.The ion dynamical motion obeys： scaling law : p>>1， dp/dt ∝ (1/p2) , p ∝ t1/3, x1/3 （T. Esirkepov et al., PRL92,175003 (2004)）

  8. Phase space (x~px) A B A B 2. One stage acceleration X. Yan et al., PRL 100, 135003 (2008) ; Bin.Qiao et al,PRL 102,145002(2009); X. Yan et al., PRL 103, 135001 (2009); M. Chen et al., PRL 103, 024801(2009);

  9. Linearly polarized laser pulse + thick solid target (2002) TNSA regime length: ld energy:67MeV Circularly polarized laser pulse + thin solid target (2008) Phase stable regime: length: tens mm energy: GeV Circularly polarized laser pulse + combination target Non-double-layer regime length:cm energy:TeV ?????

  10. 3.multi-stage acceleration for proton beam: non double layer regime The light pressure exerted on the electron layer is larger than the electrostatic pressure. The electron layer is pushed out by the ponderomotive force before double-layer is formed. matching condition:

  11. Simulation parameters： laser pusle: a0=250；foil: 20nc，D=0.5mm；gas length:12000mm，0.01nc Wakefield structure、electron and proton density double layer: Non-double layer :

  12. Wakefield structure, phase space and energy distribution of proton beam t=5000Tl t=12000Tl Maximum relativistic factor Gamma=580，Wmax >0.5TeV, 8 times higher than that in the double-layer regime

  13. Dynamical process in the non-double layer regime versus background gas density distance between the electron and proton layer maximum electrostatic field Maximum energy scaling ： maximum energy Dephasing length Minimum gas density：

  14. 4.Heavy ion toward tens TeV 4.1dynamical equation in describing the acceleration process of heavy ion Assuming the same acceleration length for both proton and heavy ion Defining the dephasing length ratio between heavy ion and proton： the maximum energy of heavy ion reads:

  15. Simulation results for carbon ion beams: the same laser and plasma parameters as given for proton beam t= 0.5Tl t= 0.6Tl In the non-double layer regime: the electron layer runs faster than the carbon ion layer . The double-layer structure can’t be formed in the laser-foil stage.

  16. Wakefield structure, electron density, carbon ion density, laser pulse t=5000Tl t=15000Tl The acceleration process is terminated at t=15000Tl ,meanwhile the laser pulse is completely absorbed, suggesting that the dephasing length is equal to pump depletion length. The inset in Fig.(d) indicating: the energy transfer efficiency converted to carbon ion is greater than 30%

  17. Heavy ion information The longitudinal phase space and energy spectrum of the trapped carbon ion at t=15000Tl Maximum energy of carbon ion versus time in unit of laser cycles (a); maximum energy for different ion with charge number Z (b). C6+ : 3.2TeV Cu29+ : 16TeV Au50+ : 25TeV

  18. THANK YOU!

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